Gas blast circuit breaker



Patented July 30, 1946 GAS BLAST CIRCUIT BREAKER Hans Thommen and Gottfried Brhlmann,

Baden, Switzerland, assignors to Aktiengesellschaft Brown, Boveri & Cie, Baden, Switzerland,

a joint-stock company Application February 18, 1944, Serial No. 522,934 In Switzerland January 20, 1943 (Cl. 13S-39) 4 Claims.

During the operation of gas-blast circuit breakers it has been found that in the bends of the pressure gas piping the velocity of flow on the discharge side of the bends is very unevenly distributed. Since the rupturing arc is, however, certain to avoid those places where there is a maximum velocity of gas ilow, only those places where the gas ow is weakest can really be effective for the extinction of the arc. This is therefore a disadvantage because it results in the rupturing capacity of the gas-blast circuit breaker being considerably reduced.

The present invention therefore concerns a pipe bend for the pressure gas piping of gasblast circuit breakers, where the aforementioned disadvantage is avoided according to the invention by providing means which so influence the ilow oi pressure gas in the pipe bends that the velocity of iiow on the discharge side of the bends is distributed approximately uniformly over the whole cross-section of the pipe.

In the accompanying drawing, Figs. 1, 2 and 3 are fragmentary views, in longitudinal central section, of portions of gas-blast circuit breakers including pipe bends that constitute embodiments of the invention.

The pipe bend a which serves either to connect together lengths of pressure gas piping or to join ie latter to the switch chamber b of a gas-blast circuit breaker not shown in the drawing, has a circular crosssection c at the inlet end and an annular cross-section d at the discharge end for the passage of the pressure gas, the planes of the inlet and the outlet ends being at a substantial angle to each other, for example 90 as shown in the drawing. In Fig. 1 the outer curved wall of the pipe bend a has a barrel-shaped bulge which is eccentric with reference to the axis of curvature, i. e., the outer portion of the Wall is formed by extending the cylindrical outer walls of the inlet and outlet ends of the pipe bend into merging Contact eccentrically of the axis of curvature. By widening the pipe bends in this manner it is possible to obtain an approximately uniform distribution of the ow velocity over the annular cross-section at the discharge end. This favourable effect can be still further increased by means of ow guides e which are located beyond the change of ow direction, as

indicated by the arrows. These flow guides can for instance consist of concentric cylinders that may be and preferably are located, as shown in the drawing, in the element adjoining the pipe bend, that is into the switch chamber or an adjoining pipe section.

Instead of providing a barrel-shaped bulge in the pipe bend it is also possible to achieve the same effect in a standard pipe bend having a circular cross-section at the inlet end and an annular cross-section at the outlet end for the passage of the pressure gas, by arranging a series of tapered ribs inside the pipe which extend along the axis of curvature, these ribs extending from the cylindrical surface of the hollow core a that imparts the annular cross-section to the discharge end of the pipe bend. These ribs can be located on a horn g which extends along the axis of curvature of the pipe bend.

We claim:

1. A pipe bend for use in pressure gas piping, said pipe bend comprising a hollow body having a circular inlet opening and an annular outlet opening in end planes at a substantial angle to each other, the inner wall of said annular outlet opening being formed by a core located within said hollow body at its outlet end, and means between said inlet and outlet end planes for effecting a substantially uniform velocity of gas flow through diierent parts of said annular outlet opening.

2. A pipe bend as recited in claim 1, wherein said means comprises tapered ribs extending along the axis of curvature of the pipe bend from said core towards the inlet end of the pipe bend.

3. A pipe bend as recited in claim 1, in combination with flow guides located in the annular outlet of said pipe bend for directing the gas along paths parallel to the axis of the annular outlet opening of the pipe bend.

4. A pipe bend as recited in claim 1, in combination with a conduit section connected to the outlet end of said pipe bend, and ow guides located in said conduit section for directing the gas along paths parallel to the axis of the annular outlet opening of the pipe bend.

HANS THOMMEN. GOTTFRIED BRHLMANN. 

